Floating-point environment

From Cppreference

C++ Standard Library
Language Utilities library Strings library Containers library Algorithms library Iterators library Numerics library Input/output library Localizations library Regular expressions library (C++11) Atomic operations library (C++11) Thread support library (C++11)
Numerics library
Common mathematical functions Floating-point environment Complex numbers Numeric arrays Pseudo-random number generation Generic numeric operations iota (C++11) accumulate inner_product adjacent_difference partial_sum
Floating-point environment
Template:cpp/numeric/fenv/sidebar content

The floating-point environment is the set of floating-point status flags and control modes supported by the implementation. It is thread-local, each thread inherits the initial state of its floating-point environment from the parent thread. Floating-point operations modify the floating-point status flags to indicate abnormal results or auxiliary information. The state of floating-point control modes affects the outcomes of some floating-point operations.

Types
Defined in header <cfenv>
fenv_t	The type representing the entire floating-point environment
fexcept_t	The type representing all floating-point status flags collectively

Functions
feclearexcept	clears the specified floating-point status flags (function)
fegetexceptflag	saves the state of the specified floating-point status flags (function)
feraiseexcept	raises the specified floating-point exceptions (function)
fesetexceptflag	restores the state of the specified floating-point status flags (function)
fetestexcept	determines which of the specified floating-point status flags are set (function)
fegetround	gets the current rounding direction (function)
fesetround	establishes the new rounding direction (function)
fegetenv	saves the current floating point environment (function)
feholdexcept	saves the environment, clears all status flags and ignores all future errors (function)
fesetenv	restores the floating-point environment without raising exceptions (function)
feupdateenv	restores the floating-point environment and raises the previously raise exceptions (function)
Macros
FE_ALL_EXCEPT	bitwise OR of all floating-point exception macros (macro constant)
FE_DIVBYZERO	floating-point exception division by zero (macro constant)
FE_INEXACT	floating-point exception inexact result (macro constant)
FE_INVALID	floating-point exception invalid operation (macro constant)
FE_OVERFLOW	floating-point exception overflow (macro constant)
FE_UNDERFLOW	floating-point exception underflow (macro constant)
FE_DOWNWARD	rounding direction (macro constant)
FE_TONEAREST	rounding direction (macro constant)
FE_TOWARDZERO	rounding direction (macro constant)
FE_UPWARD	rounding direction (macro constant)
FE_DFL_ENV	default floating-point environment (macro constant)